Total hip replacement procedures have been developed which include implanting an acetabular outer shell or cup prosthesis after appropriately preparing the acetabulum for the implantation. The actual implantation includes orienting, inserting and impacting the prosthesis in the acetabulum.
A variety of separate instruments have been required to accomplish the implantation. This has been found to be disadvantageous, particularly in view of the time and inconvenience required in switching from one instrument to another, which prolongs the overall operative time. In this connection it will be noted that a major problem encountered in performing surgical procedures such as herein referred to is the risk of infection of the operative area. This risk increases as the operative time increases, and hence it is most desirable to shorten the operative time to the greatest extent possible. Moreover, due to the nature of the procedure, it is imperative that it be performed under circumstances most auspicious to the patient and to the surgeon.
The invention disclosed in U.S. Pat. No. 4,994,064 issued on Feb. 19, 1991 to the present inventor overcomes the aforenoted disadvantages and simplifies the implantation, in that only one instrument is required for all of the segments of the procedure. With the instrument therein described an estimated fifteen to twenty minutes of operative time is saved, which is desirable for the reasons aforenoted.
The invention disclosed in U.S. Pat. No. 5,037,424 issued on Aug. 6, 1991 to the present inventor is an improvement over that disclosed in U.S. Pat. 4,994,064 in that a locking arrangement is provided for the several operative members of the instrument thereby facilitating the use thereof, and a more versatile prosthesis alignment arrangement is provided to accommodate a variety of implantation situations as may from time to time occur.
The instruments disclosed in the aforementioned prior art require several operative members which co-act to grip the prosthesis so that said prosthesis can be oriented, inserted and impacted for being properly seated, after which the instruments are released from the gripped prosthesis.
The invention described in U.S. Pat. No. 5,061,270 issued on Oct. 29, 1991 to the present inventor discloses a system for the purposes described including a simplified instrument and a disposable adapter for engaging the prosthesis removably retained thereby. The adapter engages the prosthesis in snap fit relation and the instrument removably supports an alignment arrangement whereby the system is effective for orienting, inserting and impacting the prosthesis in the acetabulum.
It will be recognized that the system disclosed in U.S. Pat. No. 5,061,270 is useful for a prosthesis of a particular size commensurate with the size of the adapter. Prostheses of varying sizes require that the adapter be changed to one of a size corresponding to the size of a selected prosthesis. When considering the arrangement of U.S. Pat. No. 5,061,270 it is discerned that it would be advantageous to have a system with the capability of accepting a plurality of prostheses, without the necessity for changing adapters, prosthesis retaining members, or the like, and including means for retaining a selected prosthesis until said selected prosthesis has been properly seated.
Accordingly, it is the object of the present invention to provide an instrument for orienting, inserting and impacting an acetabular cup prosthesis in a prepared acetabulum as part of a total hip replacement procedure, wherein a wide variety of implantation procedures can be accomplished with greater facility than has heretofore been the case. The instrument includes a head arrangement for accepting a selected one of a plurality of prostheses of various sizes and for retaining the selected prosthesis on the head until the prosthesis is seated.